• Korean Journal of Soil Science and Fertilizer
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• v.42 no.4
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• pp.307-316
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• 2009

Soil microbial activity and diversity are affected by organic sources applied to improve soil quality and fluctuate seasonally. We investigated the effects of municipal compost (MC), poultry litter (PL), and cover crops of spring oats and red clover (RC) on soil enzyme activities, and soil bacterial community-level physiological profiling (CLPP) in a Mexico silt loam in North Central Missouri, USA. Temporal patterns of these parameters were observed by periodic five soil sampling from spring to fall over a two year period. MC increased soil dehydrogenase (DH) activity consistently beginning about three months after MC application; fluorescein diacetate (FDA) hydrolytic activity significantly began to increase by the September of the first year but fluctuated during the following period. DH activity responded more directly to the amount or properties of organic residues in soils while FDA hydrolysis and CLPP were generally influenced by composition of organic sources, and enzyme activities and CLPP showed seasonal variation, which depended on organic sources and soil moisture. MC and cover crops may be useful organic sources for enhancing general soil microbial activity and altering soil microbial diversity, respectively. Because microbial activities and diversity are dynamic and subject to seasonal changes, the effects of organic amendments on these parameters should be investigated frequently during a growing season.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.1
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• pp.84-90
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• 1986

An experiment was conducted to know the effects of planting dates (March 5, 15, and 25 and April 4) and transparent polyethylene (P.E.) film treatments(tunnel, tunnel slit, and mulch) on air and soil temperatures and growth and yield of a sweet corn variety, Great Bell. Maximum air and soil temperatures and minimum air and soil temperatures were greater at tunnel>tunnel slit>mulch in that order. Differences in maximum air and soil temperatures among the P.E. film treatments were much greater than those in minimum air and soil temperatures. However, when film was opened due to high air temperature over 40$^{\circ}C$ in the tunnel, air temperature was similar but soil temperature was lower com-pared to mulch. High temperature stress could be avoided in tunnel slit without opening film by increase in the number of slits. Cold damage of corn seedlings was avoided by tunnel and reduced by tunnel slit, and frost-damaged seedlings under the mulch were recovered in few days. The number of days from planting to silking was reduced as planting date delayed. At early plantings, tunnel enhanced early growth and silking, but it delayed at late plantings because tunnel was opened during the most of day time due to high temperature. Black streaked dwarf virus(BSDV) disease was more severe at early plantings and it was reduced in tunnel slit at late plantings because plants were grown under the film at the time of infection. The number of marketable ears was similar among all treatments except mulch at March 5 planting where BSDV was severely infected. Gross income was high in tunnel and tunnel slit at March 25 planting which had more larger marketbale ears and tunnel and tunnel slit at March 5 planting which had higher market price.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.2
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• pp.117-121
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• 1990

A sweet corn hybrid, Golden Cross Bantam 70, was grown at 5 plant populations (5,000, 6,000, 7,000, 8,000, and 9,000 plants/10a) under the transparent P .E. film mulch to find the best yield evaluation method. Plant population did not affect early plant growth, culm length, ear height, and silking date. However, number of tillers at harvest decreased but leaf area index increased with increased plant population. Marketable ears were divided into two classes; the first grade of which husked ear weight over l50g (unhusked ear weight 230g) and the second grade of which husked ear weight between 100 and 150g (unhusked ear weight between 180 and 230g) according to the whole sale market price. Average length, thickness, and weight of marketable ears over 100g of husked ears decreased with increased plant population. The proportion of ears over 150g decreased with increased plant population. However, total number and weight of marketable ears and gross income per 10a calculated considering weight and number of ears increased with plant population. There were highly positive correlations between gross income and ear number or ear weight per unit area. At high plant populations the number of marketable ears was overestimated but ear weight underestimated compared with gross income. Dry matter yield of stover increased with increased plant population and ranged 755-944kg/10a with 20.7-24.5% dry matter content. Rice black-streaked dwarf virus infection rate was 10.6-14.9%, but it was not related to plant population.

• Korean Journal of Medicinal Crop Science
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• v.21 no.2
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• pp.118-123
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• 2013

This study was carried out to select optimal shade materials among four-layered polyethylene (PE) net (FLPN), aluminium-coated PE sheet (APSS), and blue PE sheet (BPSS) in condition of paddy field cultivated 6-year-old ginseng. The order of light-penetrated ratio and air temperature by shade materials was BPSS > APSS > FLPN. Light-penetrated ratio of BPSS before two fold shade was more 3 times and 2 times than that of FLPN and APSS, respectively. Air temperature of BPSS was also higher $1.6^{\circ}C$ and $1.4^{\circ}C$ than that of FLPN and APSS, respectively. BPSS showed good cultural environment because all of light-penetrated ratio and air temperature were become higher in spring and fall season but lower in summer season by additional shade with two-layered PE net. Survived-leaf ratio was highest in BPSS and lowest in FLPN causing a little water leak on a rainy day. Rusty-root ratio was also highest in FLPN because soil moisture content was increased by water leak. The order of root yield was BPSS > APSS > FLPN, and the cause of highest yield in BPSS was higher light-penetrated ratio during spring and fall season, higher survived-leaf ratio, and lower rusty-root ratio than that of APSS and FLPN. BPSS showed highest total ginsenoside content because of high light-penetrated ratio, blue light effect, and the difference in dry matter partitioning ratio such as low taproot ratio, and high lateral root ratio.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.3
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• pp.266-273
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• 1996

To obtain basic information on forage sorghum F$_1$ hybrid breeding a total of 16 lines were selected from 311 introduced sorghum germplasm accessions, assessed and classified by the taxonomic distance and principal component analysis. The lines of which plant height and morphological characters were diverse and the 50% flowering date was similar to each other, were selected for parental lines in sorghum $\times$ sweet sorghum and sorghum $\times$ sudangrass crossing groups. Three varietal groups were classified by the average linkage cluster analysis based on the D$^2$ computed in eleven characters. Group I, II and III included 6 lines of sudangrass, 4 lines of sweet sorghum and 6 lines of grain sorghum, respectively. In the result of principal component analysis for eleven characters, about 82% of total variation could be appreciated by the first four principal components, the first principal component was highly loaded with head compactness and shape, l00-seed weight, plant color and grain covering, the second principal component with flowering date, plant height and awnness.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.3
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• pp.286-291
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• 1997

This experiment was carried out to improve seedling emergence and establishment in paddy rice sown into puddled soil. Rice seed were coated with CaO$_2$, KNO$_3$ and acid sulphate soil. When coated seeds with CaO$_2$, KNO$_3$ and acid sulphate soil were sown into puddled soil, soil redox potential was increased and the period of oxidizing was longer in KNO$_3$ than that of any other soils. pH was higher in control than that of coated seeds with CaO$_2$, KNO$_3$ and acid sulphate soil. It seems that the coated seeds oxidize soil locally, thus prohibit soil reduction. Seedling emergence was improved by seed coating materials. Emergence date was 8 days after seeding(DAS) in CaO$_2$, 14 DAS in acid sulphate soil, 21 DAS in KNO$_3$ coated seed and 20 DAS in uncoated seed, respectively. Emergence rate was highest in CaO$_2$ coated seed(80％) followed by acid sulphate soil coated seed(61％), while control(46％) and KNO$_3$(42％) were very poor. This result would be interpreted as the difference in oxidizing power among coating agents ; CaO$_2$ and acid sulphate soil may oxidize weakly and shortly while KNO$_3$ may oxidize soil strongly and persistantly. Our results suggested that local oxidizing around rice seed sown into puddled soil enhanced seedling emergence and also found a possibility to promote seedling emergence with acid soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.3
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• pp.334-340
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• 2007

A super sweet corn hybrid, "Cambella 90", was grown at 5 plant populations (35,000, 45,000, 55,000, 65,000, 75,000 plants/ha) on 1 April, 1 May, and 1 June in 2004 under black polyethylene (P. E.) film mulch to find out the optimum plant populations at different planting dates. Emergence rate and percent stand increased as planting dates delayed. Culm length and ear height were highest at the planting on 1 May and increased with increased plant population. Soluble solids content was highest at the planting on 1 May and decreased as plant population increased. Ear length, seed set ear length, ear diameter, and ear weight decreased as plant population increased. Seed set ear length could not substitute for ear weight to evaluate marketable ears. The optimum plant population of "Cambella 90" was $65,000{\sim}75,000$ plants/ha at the planting on 1 April when emergence rate was low due to low temperature, $55,000{\sim}65,000$ plants/ha at the planting on 1 May, and 65,000 plants/ ha after the planting on 1 June.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.564-570
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• 1997

Field experiments were carried out to investigate the effects of different residue treatment of vetch sward on soil improvement, rice growth and grain yield from 1995 to 1996. With Chinese milkvetch, pH, Ca, and Mg of paddy soil were increased in subsoil(10~20cm soil depth), and organic matter, P$_2$ $O_{5}$, and K were increased in top soil (0~10cm soil depth). Redox potential of the paddy soil with milkvetch residue was severely reduced at earlier flooding period, and recovered gradually as rice growth continued. Weeds were more abundant in the paddy with unchanged vetch stand. The most dominant weed species in the paddy soil with vetch sward residue was Echinochloa crus-galli, followed by Leersia japonica, Polygonum hydropiper in the order of abundance. Seedling establishment ratio of rice directly sown over vetch-sward was lower than in conventional tillage paddy(no-vetch, tilled) condition. Rice growth pattern, however, was not significantly affected by vetch sward treatments. The number of tillers per square meter and plant height at heading date were not significantly different among the vetch-sward treatments. Grain yield was the highest in plough of vetch vegetation, followed by conventional (no-vetch, tilled), live-mulching of vetch, vetch-removed, and vetch-desiccated by weedcide. The whole grain rice yield was the lowest in vetch-desiccated by weedcide.

• Korean Journal of Medicinal Crop Science
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• v.16 no.6
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• pp.434-438
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• 2008

To selection of optimal shading material, two-year-old ginseng (Panax ginseng C. A. Meyer) of new cultivar, 'Cheonpoong' (CP), and native species 'Hwangsookjong' (HS) were cultured under three kinds of shading materials such as three-layered blue and a one-layered black PE (polyethylene) net (TBSB), blue PE sheet (BS), and aluminium coated PE sheet (AS) in imperfectly drained paddy soil. Growth characteristics, yield and ginsenoside contents were investigated under three shading materials. Yield and ginsenoside contents of ginseng were distinctly affected by intensity and quality of sunlight penetrated through shading materials. Light transmission ratio, air and soil temperature according to shading materials were higher in order of BS, AS, and TBSB. However, ratio of aerial phase and porosity of the soil were higher in order of AS, BS, and TBSB, respectively. There was no significantly difference in the ratio of rusty colored root by shading materials. CP showed higher stem length, leaf area, and root weight than that of HS, while the former showed distinctly lower discolored leaf ratio than that the other. Eight kinds of ginsenosides content of CP were higher than that of HS in $Rg_1$, Re, Rf, $Rb_1$ and Rc except $Rg_2$, $Rb_2$, and $Rb_3$. Total ginsenoside contents of CP was distinctly higher than that of HS. Total ginsenoside contents as affected by shading materials was higher in order of BS, TBSB, and AS in CP, while TBSB, BS, and AS in HS.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.38-48
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• 1980

To evaluate Rhizobium meliloti BALSAC, a strain selected from Canada as an acid tolerant one, and ordinary lucerne inoculant in acid condition, lucerne (Medicago sativa L. cv. Wairau) was inoculated and/or pelleted in the laboratory, and grown for two months in an acid soil (Lismore silt loam, pH 5.4) with three levels of lime in the, glasshouse. The results of controlled (noninoculated), nitrogen fertilized, laboratorial and commercial inoculated seeds were compared to give the following conclusions: 1. There was no significant difference in the top and root dry matter yields between two Rhizobium strains. However, Balsac inoculant showed higher single nodule dry matter weight and relatively higher number of larger nodules than the ordinary inoculant. 2. Lime application increased dry matter yields of plants and nodules, and the number of nodules per pot and the increase of nodules on the lateral roots in both inoculants. Lime application also caused an evenly distribution of nodules on the root by showing an increase of nodules mainly on the lateral roots. 3. Fertilizer nitrogen without inoculant slightly increased the nodulation percentage, the nodule dry matter weight per nodule and the relative proportion of larger nodules. 4. Commercially inoculated and pelleted seed showed less consistent results. 5. Relatively larger variations in measuring nodule characteristics was discussed and concluded that extreme cares should be given to reduce the variation.